Electrical control apparatus.



R. AMBERTON.

Patented Feb. 29, 1916.

2 SHEETSSHEET I.

HIS hrromfy R. AMBERTON.

ELECTRICAL CONTROL APPARATUS.

APPLICATION FILED JUNE 19, 1914. 4 1,173,334. Patented Feb. 29,1916.

2 SHEETSSHEET 2.

p I I 1 I RICHARD AMBERTON, OF LONDON, ENGLAND.

ELECTRICAL CONTROL APPARATUS.

Application filed June 19, 1914.

To all whom it may concern:

lie it known that I, RICHARD iwnnn'rox, of 5) Evelyn Mansions, Queen's Club Gardens. London, England, have invented a new and useful Improvement in Electrical (Tontrol Apparatus, of which the following is a specification.

This invention relates to improvements in electric control apparatus, and has for its objects to adapt ordinary plain rheostats for automatic control without employing any form of automatic rel *ase such as the hold-on coil and spring return hitherto employed and to interrupt the power circuit before the rearward movement of the rheostat contact arm is initiated.

Other objects will transpire in the following description.

The invention stated broadly consists in electrically interlocking a plain rheostat with an automatic switch or switches in the power circuit, by means of switch mechanism operating independently of the rheostat contact arm to automatically trip the switch or switches in the power circuit.

Stated another way, the invention consists in the combination with a plain rheostat and an automatic switch or switches in the power circuit, of switch mechanism serving to electrically interlock the rheostat and the line switch or switches and to mechanically operate the movable member of the rheostat.

Further features of the invention reside in the employment ofindepcndent no-volt and overload release devices operative in any position of the contact arm during starting and runnin and an economy switch controlled by the automatic line switch, all of which will be hereinafter described in connection with the accompanying drawings in which Figure 1 is an elevation of a plain rheostat fitted with automatic line switches and interlocking device. Fig. 2 is a side elcvation of the rheostat contact arm and operating lever. Fig. 2-, is a side elevation of one automatic line switch. and Fig. --'l is a diagram of the electrical connections.

Referring to Figs. 1 to 3, the insulating base or panel of. the rheostat designated 1 is provided with terminals 2 and 3 connected to the power circuit and with terminals l and 5 to which the armature leads of a. motor, for example, are connected. A

series of contacts 6 are connected in the Specification of Letters Patent.

Patented Feb. 29, 1916.

Serial No. 846,075.

12. .Each contact 6 carries a pin or post 13 upon which is mounted a carbon roller 14 held in place by a split pin 15 or equivalent fastening device. Pivoted on the contact arm at 16 is a contact 17 normally urged into engagement with the carbon rollers ll by a spring 18 interposed between contact 17 and :1 lug 19 on the contact arm. The object of this arrangement is for the carbon rollers to take the small spark when the brush 10 is advancing'from one contact to the next contact. Mounted upon the spindle or post 9 is an operating lever 20 provided with a substantially rectangular opening, as shown in Fig. 1, and with an operating handle on knob 21. The pin 22 on the operating lever 20 engages in a slot or ovahzed hole in the contact arm 8.

A lug '23not shown in Fig. 2on the contact arm projects into the opening in the operating lever and a spring Ql is seated at one end on this lug and at the other end on one limb of the operating lever. This spring normally keeps the contact formed by the roller 30 and part 31 open by forcing the part 20 in an anti-clockwise direction. The contact arm 3 is provided with an insulating bush 25 in which is mounted a metallic plunger 26 urged by a spring 27 into engagementwith the segmental contact 28 on the base 1. A post 29 mounted on the contact arm, but insulated therefrom, by a bush 2?), is secured in the contact arm by a nut '35 and is hollowed out at 25" to accommodate the plunger 26. This post is in ,-onductive contact with the plunger and is provided with a carbon roller 30. contact in the form of a plunger 31 is mounted on the operating lever '20 and ronductively connected therewith.

The arrangement above described provides for a relative displacement between the operating lever and the contact arm for a purpose which will hreinalter described, and also a means whereby the contact arm may be rocked. in either direction through the intermmliary of the operating lever. By moving the operating lever in a cloclnvise sense. the pin 22 engages the ,end of the slot in contact arm 8 and the plunger oration.

has been shown, and for the sake of clear- 31 engages the insulated. carbon roller to establish a circuit through one or both of tl e automatic switches which will now be described. Each automatic switch comprises a bracket 32, having an armature 33 pivoted at 3%, and. a potential coil 35 which when energized rocks the armature to close the power circuit on' one lead by moving the bridging contact into engagement with the contacts 3?, only one of which is shown in Fig. 3. The armature is bifurcated at its upper part and upon each limb a plunger 38 is mounted. These plungers are cou pled by a yol-ze 40 and engage stationary contacts it connected in parallel with brushes 3?. Springs 42 press the plungers forward and the parts are 30 arranged that the power circuit is first broken at the contacts 36 and 3'? and afterward at the contacts 38 and ll. fine or" the latter auxiliary contacts is located within. an arc chute comprising brackets e3 supporting the core or" a series wound blow-out coil 41% provided with magnetic plates and a6 disposed on either side of the auxiliary contact 41 shown in Fig. 3. The opposing surfaces ot the magnetic plates are protected by sheets of asbestos 4:7 or other refractory insulating material. The armature 33 is also provided with a post 48 arran 'ed to engage the pivoted contact lever 49 of an economy switch which is normally closed. The lever 4:9 is rocked against the influence of a spring 50 to separate the contacts 51 and The function of this economy switch will be re-- ferred to hereinafter. An overload release coil 5% controlling a core 55 fitted with current adjusting mechanism 56 serves to open the circuit of potential coil 35 at the contacts 57 and when undue overload takes place, by lifting the bridge 59.

Referring to. Fig. 4, the various parts hereinbefore described have been designated so far as is necessary to understand the op- Gne automatic line switch only ness the contact arm 8 operating lever 20 and insulated plunger 26 have been omitted. A double pole switch '30 is indicated in the power circuit, and a motor 61 connected to the rheostat terminals. The segmental contact 28 is'interrupted near each end to form two se'mrate contacts 62 and 63 of which the first is connected to contact 52 of the economy switch, while the second is connected to the segmental contact 12 and also by means of the terminal 64 to the field winding of the motor. Segmental contact 28 is connected through the economy resistance 85 with one terminal of the potential coil 35.

Assuming. the contact arm 8 to be on the firstcontact 66 of the rheostat, the spring holdingv the "plunger 31 out of contact with roller 30 switch closed, the

ope 'ation is as iollows:-By moving the operating lever so as to displace it through a small angle relatively to the contact arm to bring plunger 31 into contact with roller 30 the circuit of coil 35 is established, because, in this .sition, plunger 26 engages the segmental contacts 62 and 28. The circuit in this case being through the segment 11, arm 8, roller 30-, plunger 26, contact 62,

through the conductor to the economy switch 49, and so to the coil 35 of the automatic line switch. The automatic line switch now closes to establish the power circuit, but in so doing opens the economy switch by rocking lever 49. The opening of this switch. leaves the economy resistance in series with the potential coil and permits sufilcient current to flow to hold the switch closed. Should the circuit of coil 35 be opened during the time the economy switch is open the automatic line switch cannot again be closed until the contact arm is restored to its initial position. By means of the operating lever the contact arm is moved over the resistance contacts, but should the operating lever be released the automatic switch instantly opens the power circuit independently of the contact arm owing to the spring 2% forcing the part 20 in an anti-clockwise direction and thus opening the contact formed by the parts 30, 31. That is to say, no rearward movement of the contactarm is necessary in order to open the power circuit. The interlock thus established between the rheostat and the automatic line switch, is however, inoperative when the contact arm reaches the last rhcostat contact 67, for in this position the plunger 26 bridges con tacts 2S and 63 and shunts the interlocking device. The circuit through the switch to the motor is as follows :The current passes through the terminal 1, through the coil 54; to the economy switch 36 and from thence to the motor. From the mot-or the current returns through the terminal 5, contacts 6, through the contact arm 8 and then to the terminal 2.

At all times during running and starting the automatic line switch will serve the function of a no-volt release and similarly at all times during running and starting; the coil 54 will respond to undue overload to open the circuit of coil 35 and trip the automatic switch. Inall cases when the switch has once been tripped, the contact arm must be restored to the initial position with all the resistance in series, before the power circuit can berecstablishcd.

The advantages of the arrangement above described are that the power circuit is al- 'Ways'made and broken on a switch of the contactor type and the carbon rollers on each contact take the small spark when advancing from contact to'contact, consequently no sparking can take place on the rheostat contacts: it is impossible to move the rheostat contactarm backward in the slightest degree without first opening the automatic line switch: simple release of the operating lever opens the power circuit: the no-volt a d overload releases are out oi the control of the ope 'ator and are independent of the rheostat arm: the coil of the automatic switch cannot be burnt out however long the contact arm is on the first step: the only insulation on the rheostat. proper is the bush surrounding the plunger 26 which is not subject to mechanical strain. and finally, owing to the elimination of the main spring and the holdon coil usually employed on rheostats fitted with automatic features, a larger range of angular movement is available and a considerable increase in the amount of pressure between the brushes and contacts or plunger and segments, is permissible.

Although one embodiment has been spe cilically described in detail by way of example, the invention is not limited thereto, but includes all forms of construction falling within the ambit of the claims.

What I claim is:

1. In apparatus for controlling electrical circuits. the comliiination with a plain rheostat having multiple contacts and a movable contact arm, of an. operating lever mov-- able laterally and independently there'ot' for controlling said contact arm, an automatic line switch, and an electrical interlock between aid operating lever and said line switch.

'2. ln apparatus for controlling electrical circuits, the combination with a plain rheostat having multiple contacts and a movable contact arm, of an operating lever movable relatively to said contact arm, an automatic line switch, au interlock between said operating lever and said automaic line switch, and means for disestablishing the interlock when the operator releases handle ll. to open said automatic line switch.

3. ln apparatus for controlling electrical circuits. the combination with a plain rheostat ha ingnniltiple contacts and ainovable, coitaciarm, of an operating lever movable relatively to said contact arm, means carried by said operating lever en gaging said contact arm, an automatic line switch, an electrical interlock between said line switch. and o 'ieratiug lever, and means for i'lisestablishing said interlock when the operator releases handle Ql to open said automatic switch.

4. ln apparatus for controlling electri cal circuits, the combination with an automatic line switch, of a plain rheostat. a movable contact arm therefor, an operating lever control ing the motion of said contact arm, neaz'r erniitting of a l ited relative displacement between said contact arm and operating lever, and an electrical interlock between said operating lever and automatic line switch.

5. In apparatus for controlling electrical circuits, the combination with a plain rheostat having multiple contacts and a movable contact arm, of an operating lever movable relatively to said contact arm, an automatic line switch, independent no-volt and overload releasing devices connected with said line switch, and an electrical interlock between said operating lever and automatic line switch.

6. In apparatus for controlling electrical circuits, the combination With a plain rheostat having multiple contacts and an unbiased movable contact arm, of a spring biased operating lever movable relatively to said c ntact arm, an automatic line switch, ana an electrical interlock between said spring biased operating lever and automatic line switch.

7. In apparatus for controlling electrical circuits, the combination with a plain rheostat having an unbiased movable contactarm, of a spring biased operating lever movable relatively to said contact arm, an automatic line switch interlocked with said contact arm and independent no-volt and overload releasing devices connected to said automatic line switch.

8. In apparatus for controlling electrical circuits, the combination with a plain rheostat having a movable contact arm, of an operating lever, a lost-motion device-interposed between said contact arm and operating lever, whereby a limited relative displacement of said operating lever With respect to said contact arm takes place, a spring interposed between. said contact arm and said operating lever, an automatic line switch, a movable contact engaged by said operating lever, a stationary contact engaged by said movable contact, and an automatic line switch, established by said movable and stationary contacts.

9. in apparatus for controlling electrical circuits, the combination with a plain rheostat having a movable contact arm, of an operating lever, a lost-1notion device interposed between said contact arm and operating lever, whereby a limited relative displacement of said operating lever with respect to said contact arm takes place, a spring interposed between said contact arm and said operating lever, an automatic line switch, independent no-volt and overload releasing devices controlling said automatic line switch, a movable contact engaged by said operating lever, a stationary contact engaged by said movable contact, and an electrical interlock between said operating lever and automatic line switch, established by said movable and stationary contacts.

10. In apparatus for controlling electrical circuits, the combination with a plain rheostat having a movable contact arm, of an automatic line switch interlocked with said rheostat an economy resistance, a protective switch for short circuiting the economy resistance when the rheostat conrhcostat, of an automatic line switch, an electrical interlock between said rheostat and automatic line switch, an economy resistance, a shunt about said economy resistance, a normally closed switch in said shunt, and. means controlled by the operation of said automatic line switch to open said normally closed shunt switch when the power circuit is closecl.

In testimony whereof I affix my signature in the presence of two witnesses.

R. AMBERTON. Viitnesses N. 'l. BUnroo'r, THos. E. RoBnRTsoN. 

